IDEALIZATION OF BOND STRESS-SLIP RELATIONSHIP AT ELEVATED TEMPERATURES BASED ON PULLOUT TESTS

摘要

Bond stress-slip relationship at elevated temperatures is of great importance for estimating deflections at reinforced concrete (RC) beams and development length for prestressing steel in pretensioned members. However, still little research can be found in literatures on bond performance at elevated temperatures. In an attempt to provide an efficient formulation for bond stress-slip relationship in fire condition for steel reinforcing in RC members, an extensive experimental and analytical study consisted of two series of twenty-one rebar pullout tests of 150×300mm concrete cylinder specimens was carried out. Experiment parameters were concrete strength (24.0 and 36.9MPa) and temperature. Three of the specimens underwent the tests in room temperature and the rest, which were grouped in six sets underwent the tests in 100, 200, 300, 400, 500, and 600℃ temperatures at the rate of 3℃/min, respectively. Based on the results, the fib Model Code bond stress-slip relationship at room temperature was idealized to a set of formulations at elevated temperatures. The formulations will be implemented in a finite element (FE) modelling software to predict structural performance of RC members and evaluate anchorage performance of steel reinforcing in pretensioned members at elevated temperature.